1. Field
The present disclosure relates to network management. More specifically, the present disclosure relates to a method and system for efficient layer-2 multicast topology construction.
2. Related Art
The exponential growth of the Internet has made it a popular delivery medium for multimedia applications, such as video on demand and television. Such applications have brought with them an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches with versatile capabilities, such as multicasting, to move more traffic efficiently. However, the size of a switch cannot grow infinitely. It is limited by physical space, power consumption, and design complexity, to name a few factors. Furthermore, switches with higher capability are usually more complex and expensive. More importantly, because an overly large and complex system often does not provide economy of scale, simply increasing the size and capability of a switch may prove economically unviable due to the increased per-port cost.
One way to meet this challenge is to interconnect a number of switches to support a large number of multicast users. Interconnecting such a large number of switches in a layer-3 network requires tedious and complex configurations on a respective switch, typically performed by a network administrator. Such configuration includes assigning an address for a respective interface and configuring routing protocols for the switch. These issues can be solved by interconnecting switches via layer-2. As layer-2 (e.g., Ethernet) switching technologies continue to evolve, more flexible functionalities, such as a distributed virtualized layer-2 network across layer-3 (e.g., Internet Protocol or IP) networks, are being supported.
An efficient multicast topology is usually desirable in a network. A network administrator uses a multicast topology to manage the distribution of data traffic belonging to a corresponding multicast group in the network. A multicast topology in a layer-2 virtual local area network (VLAN) can span multiple physical layer-3 networks. A VLAN typically carries data traffic belonging to multiple multicast groups. A respective multicast group can have a different instance of a multicast topology within the same VLAN. In a VLAN, for a specific multicast group, a multicast topology represents an active data path between a respective layer-2 switch in the VLAN and the root switch/router, which is coupled to a source, associated with the corresponding multicast group. With existing technologies, obtaining such a data path is only supported in layer-3 and requires device-specific information (e.g., an IP address) of at least one router (usually the terminating router or leaf router) in the path. Furthermore, even in layer-3, only one such data path for one multicast group can be obtained at a time. Consequently, constructing a multicast topology for a multicast group can be tedious and repetitious.
While multicast brings many desirable features to a network, some issues remain unsolved in efficient multicast topology construction in a layer-2 network.